A method uses an electromagnetic tracking system, including a number of field transmitters and at least one receiver, to determine location information associated with a medical device. The method includes transmitting a set of electromagnetic signals, each signal having a frequency that is different than a frequency associated with each of the other signals, where each signal corresponds to a sum of sinusoidal functions, each of which includes an amplitude and a frequency. A field signal is received, and includes an undistorted field component and a distortion component. The amplitudes and frequencies of the sinusoidal functions are selected such that the distortion component includes a residual error arising from terms of at least a specified order in frequency. Field components corresponding to the field transmitters are extracted from the received signal, and the location information is determined based on the field components.